COMPUTER: It is an ultra fast electronic counting machine that can transmit & manipulate information.The essential components of a computer are:

i) Processor which is the brain of the computer.ii) Memory unit which stores data & instructions.iii) Disc storage unit which enables permanent storage of data.iv) Input/Output which enables permanent storage of data.v) Programs which contain instruction to the hardware.

A computer essentially consists of hardware & software.HARDWARE: The physical devices consisting of mechanical parts that make up the computer are called hardware. It includes physical components such as keyboard, monitor, electronic circuits, disc drives etc.PROGRAM: Program refers to a set of instructions to a computer to perform a task. The program may be as simple as written to add 2 numbers & as complex as for weather forecasting.SOFTWARE: A collection of program forms software. Without software, hardware cannot work.TYPES OF SOFTWARE: It is mainly classified into two categories

1) SYSTEM SOFTWARE: It is a collection of programs needed to operate & control the functioning of a computer. These are the software which provides the environment for writing & running the application programs. These software include

a) Opening system which acts as an interface between the user & computer hardware.b) The service programs like compilers & interpreters which are used to develop application programs.

EXAMPLES: MS DOS C compiler Basic interpreter

2) APPLICATION SOFTWARE: These are the software which enables us to carry out specific tasks on the computer.This type of software consists of a set of programs to carry out operations for specific tasks on the computer and specific application programs.E.g.: a) AutoCAD b) Computerized billing system, inventory, package etc.. c) Tally

CAD SYSTEM: The process of model creation, analysis & evaluation of an engineering design through the use of computers is known as Computer Aided Design. CAD system consists of computer hardware & associated software. While the software parts consist of implemental aspects of the design methodologies, the hardware resources assist in executing of this software. The hardware includes the computer graphics terminals & the peripheral devices. The software parts consist of the computer graphics for the user interaction of the application program for design. In

a CAD system the user enters the necessary information about a part like geometrical details through interactive computer graphics with the help of input devices like mouse or keyboard. ICG is a user friendly environment having a graphical user interface which facilitates user interaction with the CAD system. These inputs are used by the application program to continue with further processing like creating model, assigning constraints & carrying out analysis. Model can be created by involving entity creation modification commands. The results of design analysis can be obtained by making use of the output devices like printers, plotters, etc.

HARDWARE IN CAD: CAD hardware is required for the following purposes as listed.

1. Input of information regarding model2. Output of engg.dwg. of the model created.3. Processing of the input information about a model for its design details.

CAD system should be powerful enough in terms of computing power & graphics capabilities. The input devices can be keyboard, mouse, digitizer, etc. A graphics terminal should support graphical user interface provided by the CAD software. The output devices can be printer or plotter. The secondary storage media assists in taking the back ups of the CAD information on storage devices like floppy discs, CDs, DVDs, Pen Drives, Portable HD. The CPU is the main controlling part of the entire CAD system. The processor should be fast enough to handle huge amount of information & carry out complex mathematical equations.

OPERATOR INPUT DEVICES: Interactive computer graphics requires user to input information through different means into the graphics package. At the same time user should be able to modify graphics entities even of small details. The user should also be able to draw the images interactively & in real time. In a design work station, a number of input devices are available. All these devices can be grouped into three categories.

1) Cursor control device2) Digitizer3) Keyboard terminal

CURSOR CONTROL DEVICES: These devices control the position of a bright spot on the graphic screen. The movement of this bright spot is sensed by the CAD system & the graphic image can be created by clicking on information about the co-ordinates location. The various cursor control devices are as follows:

MOUSE: It is the most popular input device. A mechanical mouse consists of wheels placed orthogonally at the bottom of the mouse. These wheels get actuated for movements of the mouse along x & y axes. The values are recorded by pressing the mouse buttons. In optical mouse system the light source is provided on the button with an optical encoder.

DIGITIZER: Digitizer boards or tablets are electro-mechanical vector graphic input devices that resemble a drafting board. These are used together with a movable stylus called puck. The puck can be moved over the surface to following existing lines. It is a common technique in CAD systems for taking x and y co-ordinates from a paper drawing. The

tracking device (puck) contains a switch for the user to record the desired x and y co-ordinates. The co-ordinates are either directly sent to the computer or stored in secondary storage devices like magnetic tapes. Digitizers with a large board provide high resolution and accuracy. Digitizers are more frequently used to create drawings using an interactive drafting package to enter a sketch or a drawing which can be redrawn or edited as the display appears on the CRT screen.

KEYBOARD TERMINALS: It is an alphanumeric terminal used to enter commands, co-ordinates, functions and process data to the CAD system. The information typed is displayed on the CRT screen. The typed information displayed on the CRT screen can be changed. CAD systems make use of special function keyboards. These function keys are provided to eliminate extensive typing of commands. The number of function keys varies from about 8 to 80.

AutoCAD: AutoCAD is a highly professional computer aided design & drafting package which can run on low cost microcomputers. AutoCAD brings the benefits of sophisticated technology which was previously available to large & costly system, within the reach of desktop.For a computer user, AutoCAD is easy to learn and one need not possess any previous computer experience & knowledge to get started in Auto CAD. The set of menu are user friendly & easy to follow. Drawings of any size can be created & revised. The drawing can be stored on floppy, hard disc, CDs, DVDs or pen drives and can be plotted to any scale.There is virtually no limit to the kind of drawing one can prepare using AutoCAD. It is very successfully applied in areas such as

1) Architectural drawings2) Interior design & facility planning3) Drawings of various engineering applications in mechanical, electrical, civil, automobile, chemical and

electronics engineering 4) Technical illustrations & assembly drawings.5) Graphs & plates of all kinds.6) Geometric modeling.

DEVELOPMENT OF AUTO CAD: The computer aided drafting system; AUTO CAD was launched in December 1982 by Autodesk Inc. of USA (version 1.0). Additional features and facilities were added and enhanced versions followed one another in quick succession release 2.1 in May 1984, version 2.1 in May 85, version 2.5 in June 86 & version 2.6 in 87. The latest version is AutoCAD 2010 which is its 24th release.

SYSTEM REQUIREMENT: AutoCAD runs on a wide range of low cost industry standard computers. AutoCAD files are compatible between different market types & their operating systems. You can easily exchange information between different computer systems. AutoCAD supports a wide range of peripheral devices including digitizers, mice, high resolution display monitors, pen plotter, dot matrix printers, electromagnetic plotters etc…

The following are the system requirements for running AutoCAD 20041) Intel Pentium III or later, with 800 MHz or faster processor, or compatible2) Microsoft Windows XP (Professional, Home Edition, or Tablet PC Edition)3) Windows 2000, or Windows NT 4.0 (SP6a or later)

4) 256 MB RAM5) 300 MB free disk space for installation6) 1024x768 VGA with true colour (minimum)7) Microsoft Internet Explorer 6.08) Mouse, trackball, or compatible pointing device9) CD-ROM drive

Optional:1) Printer or plotter 2) Digitizer 3) Serial or parallel port4) Network interface5) Modem or access to an internet connections

WRITE A PROGRAM INVOLVING THE PROPER SETTING AS PER AUTO-CAD DRAWING.

The following commands are used in setting the proper style:The Auto CAD drawings are typically drawn at full size. The scale is set at the time of printing. The command helps to select any unit system or degree of precision. It also controls the direction of angle measurement, whether clockwise or anti- clockwise. The starting position of measurement can also be changed. The default is zero degree to the right side and counts clockwise. Precision contracts the decimal place displayed on the state line and in dimensions.Following settings have to be done:Type : DecimalPrecision : 0.00Angle type: Decimal degreePrecision : 0.00Clockwise : It can measure clockwise direction.Direction : To specify position of a measuring direction.Units : S I units.

LIMITS : Drawing limits is the invisible boundary to fill the drawing. It should be large enough to contain the drawing and its related parts.

Command: Limits press enter.Menu : Format – drawing limitsSpecify lower left corner or [on/off] (0.0000) enter lower co-ordinates value (0, 0) and press enter.Specify upper right corner (420, 297). To change the upper limits enter upper co-ordinate value (x, y) as per the standard drawing sheet size and press enter.

GRID and SNAP:The grid gives a visual display of position on the screen but it is not possible to pick exact position only by eye adjustment. So an option is given to set snap distance. When snap is set the cursor movement is restricted and the cursor will only move in steps of the snap distance.

COMMAND: grid press enter

Command: snap press enterMenu: Tools – drafting settingsKeep snap on & specify value (5)Keep grid on & specify value (5)View – zoom - all.

WRITE TWO FUNCTIONS & PROCEDURE OF THE FOLLOWING COMMANDS.1. Line2. Arc3. Circle4. Ellipse5. Polygon6. Rectangle7. Donut8. Points

1) LINE: Command: Line or ‘L’ press enter Menu: Draw-LinePick start point, pick next point.Use undo to cancel previous line.Use close to join the first & last points.

The following methods are used to draw the line to given size.a) GRID METHOD:b) STATUS LINE METHOD:

Status line shows distance & direction.c) POLAR METHOD:

After selecting the 1st point specify length & direction in the format at length & direction.d) DIRECT DISTANCE METHOD:

Pick start point, keep cursor on required direction & enter the distance.

2) ARC: Command: Arc or ‘A’ press enter Menu: Draw-Arc a) THREE POINT METHOD: Pick start point, second & the end point

b) START CENTRE END: Pick start point, the centre & pick end of the arc.

c) START CENTRE ANGLE: Pick start point, pick centre or the line & enter the angle. d) START, END, ANGLE:

Pick start point, end point & specify the angle.

DEFINITION: Arc will continue from the end point as previous arc or any other object drawn. Arc will continue in the same direction as the previous object.

3) CIRCLE:Command: Circle or C, press enter Menu: draw-Circle-option.Various options are the following –

a) CENTER RADIUS: Pick centre point or the centre co-ordinate as the centre point; specify the radius using the keyboard.b) CENTRE DIAMETER:Pick the centre or the centre co-coordinating as centre point, specify the diameter using the mouse or enter the radius using keyboard.c) 2 POINT:

Circle passes through specified 2 point or diameter point .pick the 1st &2nd point.d) 3 POINT:

Circle passes through specified 3 point select 1st, 2nd & 3rd point.e) TAN TAN RAD: Draw a circle tangential to the selected object. Select 1st, 2nd, & 3rd object.

4) ELLIPSE: Command: ellipse or El press enter Menu: Draw- ellipse-option. a) CENTRE: Pick centre, end & other axial distance b) AXIS END: Pick axis end, 1 axis end & the other axis end distance. c) ARC: Pick axis end, 2nd axis end, other distance start of arc & end of arc.

5) POLYGON: Command: polygon or pol press enter Menu: Draw –polygonEnter number of sides Pick Centre Enter the radius or pick the radius.For the polygon to be in edge condition, pick edge from screen menu.

6) RECTANGLE: Command: rectangle or rect press enter Menu: draw—rectangle Pick on corner, pick opposite corner or enter length &width. The various values are

i) Characterii) Elevationiii) Filletiv) Thickness &Width

7) DONUT: Command: donut or do, press enter Specify inner &outer diameter of donutSpecify centre of donutTo fill mode ON/OFFMenu: tools--option--display--apply

8) POINTS: Command: point or po press enter Menu: draw -- point -- option Single point only one point at selected location Multiple points create a series of point at selected location

EXPLAIN VARIOUS SELECTION METHODS:To select object following method may be used

i) Selecting by pick box.ii) Direct windows, pick a point at empty place to cover the object & change the right side. In this

method, objects which are completely within the windows will be selected.iii) Crossing windows : if selection is from right –left all objects which are within the windows &

passing through the windows will be selected.

EXPLAIN FOLLOWING FUNCTION

A) MOVE: To shift objects from one place to another Modify –move Select object, press enter Pick base point, pick displacement point. B) COPY: To get one or more number of copies as selected objectModify –copySelect the objects, press enterPick base point (copy) or pick duplicate then base point (move copies)Pick displacement copies.

C) ROTATE:

To rotate the object about a given axisModify – rotate Select the objects, press enterPick the base point Enter angle of rotation by keyboard or key using mouse

D) BREAK: To cut off object at one point in between two points Modify –break— option

i) select second – select object, pick a point ii) select point – select object at a point to breakiii) select point – select object pick, 1st & 2nd points iv) select 1st point – select object , pick a point

E) TRIM: To cut off extended edge or point of intersectionModify—trimSelecting cutting edge, press enterPick edges to trim.

F) EXTEND: To extend the open end of an object Modify-extend Select boundary, edges, press enter Pick edge to extend

G) ARRAY: To get a number of copies of object of given area, Row or column or around an image Modify-array Select the object, press enter Select the type of array

H) SCALE: To increase or release the size of object proportionally modify- scale, select object press enter, pick the base point, enter scale factor. EXPLAIN VARIOUS LINE TYPE & COLOURS IN THE DRAWING BEING USED:

i) Properties to change color & line type method. Method 1: select object.

Modify-properties Change color and line type or required

Method 2: select object Using object properties for change color & line type.Select before changing the line type, lines or type to be located or loaded Format- line type – load.Select required line type from the task click ok.

ii) LT scale control the sizes of dashes. Command: lTscale, press enterSpecify the value.

EXPLAIN BRIEFLY THE FUNCTION OF LAYER CONTROL:By default the layer available for drawing when new file is created is “0”. User can create as many layers he/she wants. Each layer will have an associated colour and linetype which can be changed. Layers can be used to distinguish between various parts getting assembled together. Layers of objects can be made visible and invisible whenever required. The functions of layer control are –

To create new layer To change the color To change the line type To draw object or particular layer To free the layer

WHAT IS THE USE OF DIMENSION IN DRAWING &EXPLAIN HOW TO USE HATCHING

a) LINEAR: To draw the horizontal & vertical dimensions specify first extension line origin. Specify second point on the object Pick dimension line location.

b) ALIGNED: The dimension line will be aligned to section points specify first extension line origin or select object Pick 1st extension point.Specify 2nd extension line originPick 2nd extension point.

c) ORDINATE :It shows x & y co- ordinate at selected point Specify feature location: select a point, specify point.

d) RADIUS:

It shows radius of selected circle with a prefix R select arc or a circle. Pick arc or circle.

e) DIAMETER:To show diameter of selected arc of circle with prefix ØSelect arc or circle: pick arc or circleSpecify dimension line location.Pick a position.

f) ANGULAR:To measure & write angles in between select the object or included angle of axis, select arc ,circle, line or ( specified vertex) .pick object specify 2nd angle end point. Pick an object specify dimension one line location, pick position.

g) LEADER:To create a line to lead a point for the text item.Specify 1st leader or point: pick a point.Specify next point: pick 2nd point.Specify next point: (format / annotation/ undo)<annotation > continue.Select a point or press enter.Specify 1st line & annotation list Type required text press enter.

h) BASE LINE: To create parallel dimension create one dimension using any method then click “baseline”. Specify a 2nd extension origin. Select 2nd extension point.

i) CONTINUOUS: To put chain dimension Create 1stdimension & the chain using any method then click “continuous”.Specify a 2nd extension origin: select 2nd extension point.

DIMENSION STYLE:

Menu: Format – Dimension Style – Modifyi) Line and Arrows:1) Color of dimension line.2) Color of extension line.3) Dimesnion line visible, invisible.4) Type of arrow head.

5) Type of centre line and head work. ii) Text appearance:

1) Self required style for text.2) Select colour for text.3) Specify size for text.4) Text placement, vertical, horizontal, offset form dimension line.

iii) Primary units:1) Unit format: Controls the system of units in dimension.2) Precision: Controls the dcimal place or fraction of unit appearance in dimension value.3) Decimals Seperators: Select the type and seperator which appear b/w whole no of fractional value of

the dimensions.

HATCHTo hatch an area, choose Hatch from the Draw toolbar. This starts the BHATCH command. The Hatch dialog box opens. Use the dialog box to define your hatch. Pick the area for hatch by either picking a point within the area or by selecting objects which defines the hatch area. Select appropriate hatch pattern, angle and scale.

HOW TO DRAW AN ISOMETRIC VIEWS USING A CAD MENU.Menu: Tools - drafting settingIn snap type keep isometric snap on.

EXPLAIN THE PROCEDURE TO WRITE TEXT IN DRAWING.Text plays an important part of drawing or is used to title blocks to table the parts of the drawing. There are 2 types.

i) Multi line text.ii) Single line text. Menu: draw—text—single line text / multiline text /style / (art point); pick a point.Rotation angle: enter angle for text line.Press enterText: type the text required.

EXPLAIN PROCEDURE OF BASIC SOLID OBJECT CREATION.Object like box, cone, cylinder, sphere, edge etc can be created by using solid commands menu & by specifying the dimension as the objects. Menu: Draw—solid—option. 1) BOX:

Specify corner as box or pick pointer & enter specify the opposite corner. Pick points & enter specify height. Specify a value, press enter

2) WEDGE: Specify the opposite corner or edge or pick a point specify corner or Pick opposite corner specify height. Specify a value. Press enter.

3) CONE: Specify centre point for base of cone or pick centre point or type for elliptical cone. Specify the radius for base of cone. Enter height of cone and press enter.

4) CYLINDER: Specify centre point for base of cylinder pick centre point or type for elliptical cylinder. Specify radius for base of cylinder or enter radius & press enter. Specify the height of cylinder or specify a value for height press enter.

5) SPHERE: Specify centre as sphere a point sphere radius of sphere or specify a value press enter.

EXPLAIN THE FOLLOWING COMMANDS:

1. EXTRUDE : Changes 2D objects into 3D objects by giving thickness to selected objects. It can also create tapered objects. Command: extrude or ext press enterMenu: draws- solid- extrude.Select object: pick objects to extrude press enter.Path specifies a value for thickness press enter.Specify height as expansion or if necessary specify an angle for taperness enterSpecify angle of taper for extension

2. REVOLVE :Revolve creates a 3D object by revolving a 2D object around an axis. The 2D object should be a closed object. Command: revolve or rev press enterMenu – draw- solids- revolveSelect the object: pick object s to revolve specify.Start point for axis of revolution or define axis by pick start of axis.

3. SLICE: A new solid can be created by cutting the existing solid or by remaining one part of it. The objects may be cut in any direction along the specified cutting plane. Command: slice or s press enter.Menu: draw –solids- sliceselect objects, pick objects to cut press center specify first point on sliding plane by option pick 1 point on cutting plane specify 3 point on plane pick 3 points on cutting plane specify the point on desired side on the plane or pick a point on the sides to retain or type B as both sides are to be retains.

4. UNION:

This command is used to combine two or more solid objects together forming one composite object, the overlapping area of objects removed while joining them to make a composite solid. Single Object:Command: Union, press enter.Menu: Modify – solid adding – UnionSelect objects: Pick objects to union press enter.

5. SUBTRACT:Used to subtract one solid from another. This command is mostly used to create holesCommand: subtract press enter.Menu: Modify – Solid editing – subtract.Select solids and region to subtract select object, pick object to remove from previous set by selected objects press enter.

6. SECTION: Uses the intersection of a plane and solid to create a region.Command: Intersect or in press enter.Menu: Modify – Solid adding – Intersection.Select object: Select intersecting objects press enter.

7. INTERFERENCE:Creates a composite 3D solid from the common volume of two or more solid objects. Command: Interference press enter.Menu: Draw – Solids – Interference.

EXPLAIN THE PROCEDURE OF TAKING PRINT OUT OF 2D DRAWING

The procedure of taking print out of 20 drawing:Menu: File – plotPlot dialog box will appear. It consists of 2 main operation i.e., plot device and plot setting. Plot device option is used to set up the printer’s device and its configuration plot. Setting is used to select suitable, printer, paper size, drawing area etc. Select connected printer and other details as required. Select the paper size of units required. In plot area, click on windows and select area to be printed. Using plot offset position the drawing at centre by selecting centre the plot. Click on full preview at plot will appear with a zoom. Press right button on the menu. If preview is correct, click on plot to get print out. If preview is not correct, click on exit.

Then change any options to get print out. The printing device is to be on and paper is to be set properly before using plot command.

WHAT ARE THE VIEW ENHANCEMENT COMMAND FOR 3D OBJECTS. EXPLAIN

1.HIDE: When a 3D object is created, its back side also visible. But when we view real life 3D objects, back side edges of objects are not visible. To make back side edges of objects invisible, hide command is used.Command: Hide or H press enter.c) SHADE: This option provides shading for wire frame options for 3D objects. Command: Shade or press enter.d) 3D Object Views: For paper viewing of the full details of 3D objects, the viewing angles to be changed. This can be closed using “V” Point command.Menu: View – 3D views.

DEFINE U.C.S AND WHAT IS THE USE OF U C S WHILE CREATING OBJECTS.To create complete object it is necessary to draw some object on different surface at different angles. Therefore using U.C.S., drawing can be done with ease and accurately. UCS can be moved to a new place or rotated at its existing place in order to draw different features.

DIFFERENCE BETWEEN “WIRE FRAME MODELLING AND “SOLID MODELLING”.

WIRE FRAME MODELLING:

A wire-frame model of 3D object consists of finite set of points together with edges connecting these pair of

points. An edge may be straight line, arc or any other curve. Thus the above point data can be manipulated

to produce any required orthographic or perspective projection. In wire-frame modelling the edges of the

objects are shown as lines and image appears like a frame constructed of wire, hence it is named as wire-

frame modelling.

SOLID FRAME MODELLING:

In solid modelling, the models are displayed as solid objects. Solid models are easier to generate than wire-frame models. Solid models are ideal for colour and animation projects. For a solid image any colour can be added, resulting picture become realistic. In solid modelling mass property analysis, interference checking, FEA, collision checking can be done.